I designed a ring that involved some screw threads and took a chance printing it in Silver. I realized it would be difficult to print screw threads that actually functioned, but I just wanted to test out Silver to see how strong and detailed it could get. To my surprise, when the part arrived the threads were smooth and perfect and I was able to screw things into the ring beautifully.

I was thinking of offering this ring for sale, but about a month later I ordered another copy. Same model, same Silver. When it arrived, the threads would not work at all. Also, the surface of the Silver seemed much more coarse and rough. This carried over onto the threads, which is why they will not work.

The photo below shows the two side-by-side. The one on the left is the new one, and the one on the right is the first one I received. The surface difference is clear in the picture.

I am new to 3D printing, and I had expected that computer printed parts would be identical. Is it possible that the second ring was printed at a lower resolution that the first? Or is the printing process just not as precise as I was expecting?

I am happy to have my first part which works so perfectly. I'd love to get another one just like it but Silver is too expensive a material to order and pray.

First silver isn't 3D printed. It's printed in wax, and a lost wax casting is done on it to produce the final silver piece. And 3D printed items themselves can have slight variations depending on print orientation, and a few other factors.

I'd email support (service@shapeways.com) with your images and see what they say could have caused the differences. I don't think the threading would come out every time, but the rough surface might be something gone wrong.

I learned a long time ago the wisest thing I can do is be on my own side, be an advocate for myself and others like me. -Maya Angelou
michael@shapeways.com Community Advocate